Celestron 1.25" Cheshire Collimating Eyepiece for Newtonian Reflectors
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The Celestron Cheshire Collimation Eyepiece is ideal for precise collimation of Newtonians and helpful for aligning Schmidt-Cassegrains. This special eyepiece fits into 1.25" focusers or diagonals.
Alignment is easy using the small opening on one end and thin cross hairs at the other end. The collimation eyepiece is more accurate than the simple Collimation Tool.
Item weighs 5.2oz. Total length is approx. 143mm / 5.64". Insertion length is 102mm / 4.02". Please see schematic diagram in photo 3 above for detailed measurements.
Given the dimensions of this Cheshire, it’s possible to sight the full aperture of the primary and secondary of a Newtonian with a focal ratio of approximately f/5 and slower. With faster scopes, it may be necessary to pull the Cheshire out of the focuser somewhat to see the outer edge of the secondary and adjust it so it’s in the center of the field. This adjustment is usually required if the secondary is removed from the tube and replaced, or if it was badly positioned at the factory. When the Cheshire is pulled out slightly, it may be difficult to see the edge of the primary, but if the primary has an accurately placed center dot, alignment remains straightforward. For example, we’ve used this Cheshire to quickly collimate Newtonians with a focal ratio of f/4.7. For scopes with focal ratios of f/4.5 or faster, a shorter Cheshire or sighting tube (or a laser collimator) may be required because of the large secondary.
Product carries full 2 year Celestron factory limited warranty (within US/Canada only).
Other Information
- Country of Manufacture: China
The Celestron Cheshire Collimation Eyepiece is ideal for precise collimation of Newtonians and helpful for aligning Schmidt-Cassegrains. This special eyepiece fits into 1.25" focusers or diagonals.
Alignment is easy using the small opening on one end and thin cross hairs at the other end. The collimation eyepiece is more accurate than the simple Collimation Tool.
Item weighs 5.2oz. Total length is approx. 143mm / 5.64". Insertion length is 102mm / 4.02". Please see schematic diagram in photo 3 above for detailed measurements.
Given the dimensions of this Cheshire, it’s possible to sight the full aperture of the primary and secondary of a Newtonian with a focal ratio of approximately f/5 and slower. With faster scopes, it may be necessary to pull the Cheshire out of the focuser somewhat to see the outer edge of the secondary and adjust it so it’s in the center of the field. This adjustment is usually required if the secondary is removed from the tube and replaced, or if it was badly positioned at the factory. When the Cheshire is pulled out slightly, it may be difficult to see the edge of the primary, but if the primary has an accurately placed center dot, alignment remains straightforward. For example, we’ve used this Cheshire to quickly collimate Newtonians with a focal ratio of f/4.7. For scopes with focal ratios of f/4.5 or faster, a shorter Cheshire or sighting tube (or a laser collimator) may be required because of the large secondary.
Product carries full 2 year Celestron factory limited warranty (within US/Canada only).
The Celestron Cheshire Collimation Eyepiece is ideal for precise collimation of Newtonians and helpful for aligning Schmidt-Cassegrains. This special eyepiece fits into 1.25" focusers or diagonals.
Alignment is easy using the small opening on one end and thin cross hairs at the other end. The collimation eyepiece is more accurate than the simple Collimation Tool.
Item weighs 5.2oz. Total length is approx. 143mm / 5.64". Insertion length is 102mm / 4.02". Please see schematic diagram in photo 3 above for detailed measurements.
Given the dimensions of this Cheshire, it’s possible to sight the full aperture of the primary and secondary of a Newtonian with a focal ratio of approximately f/5 and slower. With faster scopes, it may be necessary to pull the Cheshire out of the focuser somewhat to see the outer edge of the secondary and adjust it so it’s in the center of the field. This adjustment is usually required if the secondary is removed from the tube and replaced, or if it was badly positioned at the factory. When the Cheshire is pulled out slightly, it may be difficult to see the edge of the primary, but if the primary has an accurately placed center dot, alignment remains straightforward. For example, we’ve used this Cheshire to quickly collimate Newtonians with a focal ratio of f/4.7. For scopes with focal ratios of f/4.5 or faster, a shorter Cheshire or sighting tube (or a laser collimator) may be required because of the large secondary.
Product carries full 2 year Celestron factory limited warranty (within US/Canada only).
Other Information
- Country of Manufacture: China
Celestron 1.25" Cheshire Collimating Eyepiece for Newtonian Reflectors